Exploring\nEnergy-Density Relationships in Uranyl nun-Topology\nMOFs and Their Topological Isomers

Metal–organic frameworks (MOFs)\noffer a tunable\nand controlled\nenvironment to investigate uranium chemistry, though the development\nof specific design rules for uranyl-containing MOFs remains necessary.\nHere, we explore the previously reported low-density uranyl MOF, NU-1301,\nto investigate the formation of additional topologically unique products\nand their thermodynamic relationships. By adjusting the temperature,\nmodulator, and reaction time, we selectively synthesized three distinct\nphases: NU-1301-A, NU-1301-B, and NU-1301-C. We further examined their\nenergetic relationships by analyzing the conditions that trigger the\ntransitions between them. This approach was applied to the synthesis\nand study of an isoreticular analogue, NU-1308, and its topological\nisomer, NU-1309. Our findings reveal that the lower density <b>nun</b> topologies, NU-1301-A and NU-1308, are kinetic products,\nwhile the higher density structures, NU-1301-B, NU-1301-C, and NU-1309,\nare thermodynamically more stable. Understanding these energetic profiles\nis valuable for the reproducible synthesis of low-density MOFs and\nfor identifying structure-energy relationships in the crystallization\nof actinide-containing materials.